“服务器宕机了！”
“我无法登录服务器。”
“服务器已满负荷。”
这些是我们在使用互联网时每天听到的那种短语，但究竟什么是“服务器”。这是每个人都使用的术语之一，但很少有人真正了解任何细节。
您很有可能通过键入“什么是服务器？”找到这篇文章。进入搜索引擎。这没什么好丢脸的！这是任何互联网用户都应该知道的基本知识，您将在这里获得所有基本信息。
互联网实际上是什么
要了解服务器是什么，您必须首先了解互联网（或任何计算机网络）是什么。对于大多数人来说，互联网就像电一样。你把一根电缆插入墙上，互联网就从它里面出来了。正如大多数人不了解发电站的内部运作一样，大多数人并不真正了解网页(how )、视频流或电子邮件等互联网服务的工作原理。
这个概念实际上很简单。互联网只是通过通信硬件（例如路由器和网络电缆）连接在一起的计算机集合。
每当您访问网页、观看视频或发送电子邮件时，世界上的某个地方都会有另一台计算机在提供内容或充当中间人来帮助您与其他人交流。
什么是服务器与客户端
这些提供服务的计算机就是(SERVices)我们通常所说的“服务器”。接收这些服务的计算机称为“客户端”。看？这是一个非常简单的概念。服务器为客户端提供内容和服务。但是，这并不能告诉我们有关服务器本身的太多信息。它们到底是什么？
服务器只是计算机
任何计算机都可以是服务器。您的家用计算机可以是服务器。尽管您的互联网服务提供商可能禁止家庭互联网订阅的做法。它也不仅仅是传统的台式电脑。任何联网的计算机都可以充当服务器、客户端或两者兼而有之。
“客户端”和“服务器”的概念不是对特定设备的描述，而是描述计算机在网络上的角色。例如，如果您有一个 IP 安全摄像头，那么这些摄像头会在其微型嵌入式计算机上安装服务器软件。当您访问相机时，您将登录到为您提供视频流的服务器。
话虽如此，并非每台计算机都适合充当服务器。经常使用“服务器”一词时，它指的是从头开始构建的专门用作服务器的专用计算机。
服务器硬件很特殊
如果您要冒险进入网站托管公司的典型服务器机房，您会看到一排排的机柜。在这些机柜内，您会看到堆叠在一起的服务器机架。如图所示。
在每个机架内，您都会发现一个特殊的服务器级主板、RAM、CPU和存储。原则上，这些组件与您计算机中的组件相同。除了在服务器内部，它们更强大、更可靠、更节能。毕竟，这些计算机每天 24/7 全天候工作，每天为来自客户的数百万个请求提供服务。
这就是为什么服务器硬件比您在消费类 PC 中找到的东西贵得多的原因。服务器每(Every)停机一分钟都可能造成数千美元的损失。因此，值得支付额外费用以确保相关互联网服务仍然可用。
我们不会在这里深入细节，但服务器硬件在以下主要方面脱颖而出：
- 服务器主板支持大量RAM。在许多情况下价值 TB！
- 服务器(Server)主板通常有多个CPU插槽
- 服务器 CPU(Server CPUs)往往具有许多CPU内核和大量缓存
- 服务器内存(Server RAM)通常是一种特殊的纠错类型，以确保稳定性
- 服务器(Server)电源可能是冗余的，如果主机出现故障，会立即切换到备用电源
机架式服务器也没有键盘、鼠标、屏幕或扬声器。相反，它们是通过网络通过命令行或使用远程桌面应用程序访问的。尽管它们通常确实具有连接这些外围设备所需的端口（如果需要）。
本地服务器
“本地”服务器是在您的本地家庭网络上运行的服务器，而不是互联网上“外面”的某个地方。
您很有可能在您的一台家用计算机上运行某种服务器应用程序，但您甚至不知道它。上述 IP 摄像头嵌入式软件就是一个例子，但在常规台式机和笔记本电脑系统上运行的其他应用程序也符合要求。
例如，流行的Plex应用程序在您的本地计算机上运行媒体服务器。这就像在您的本地网络上运行的Netflix 。Calibre充当电子书的本地文件服务器，当然，网络附加存储设备也是一种本地网络服务器。因此，如您所见，服务器无处不在。甚至在你家！
常见的服务器类型
虽然所有服务器都有相同的一般工作，但有明确的服务器子类型专门从事不同的任务。
Web 服务器(Web servers)(Web servers)非常普遍。您此时正在阅读的网站是由网络服务器发送给您的。您的网络浏览器充当客户端并从服务器请求网站数据。然后它接收HTML（超文本标记语言(Hypertext Markup Language)）网页代码并将其呈现到您的屏幕上。从那里它进入你的眼球，这个信息现在在你的脑海里。整洁(Neat)，对吧？
文件服务器(File servers)(File servers)使用 FTP 或文件传输协议(File Transfer Protocol )标准而不是HTML，并且存在将文件从自己的硬盘驱动器移动到您的硬盘驱动器。
电子邮件服务器(Email servers)(Email servers)处理电子邮件消息的发送和接收。基本上(Basically)它是一个电子邮局。
名单还在继续。有用于验证登录详细信息的服务器、充当公司计算机和互联网之间代理的服务器、Netflix等公司的流媒体服务器等等。随着越来越多的互联网服务被发明出来，随着时间的推移，我们可以期待新型专用服务器硬件和软件的出现。
“大型机”与“服务器”
最后一个混淆点是“大型机”计算机和服务器之间的区别。虽然服务器本质上是增强型台式计算机，但大型机是完全不同的野兽。
这些计算机比服务器硬件强大得多。对可靠性和备用处理能力的重视要高得多，这些计算机通常用于关键任务的工作。
网上(Online)银行是大型机可能是更好选择的一个例子。特别是因为大型计算机的构建是为了通过尽可能多的“事务”进行压缩。这些计算机通常有一个大冰箱那么大。通常，它们有十台机架式服务器那么大。
有人为你服务吗？
希望您对什么是计算机服务器的好奇心现在已经减弱。当然，这些只是基础知识，但现在至少你知道你的模因在到达你的屏幕之前来自哪里！
HDG Explains : What Is a Computer Server?
“The server is down!”
“I can’t log into the server.”
“The servers are at capacity.”
These are the sorts of phrases we hear on a daily basis when using the internet, but what exactly is a “server”. It’s one of those terms that everyone uses, but few people really know any details about.
There’s a good chance you found this article by typing “What is a server?” into a search engine. It’s nothing to be ashamed of! It’s an essential piece of knowledge any internet user should know and you’re about to get all the essential info right here.
What the Internet ACTUALLY Is
To understand what a server is, you must first understand what the internet (or any computer network) is. For most people the internet is like electricity. You plug a cable into the wall and the internet comes out of it. Just as most people don’t know the inner workings of a power station, most people don’t really understand how those internet services such as web pages, video streaming or email work.
The concept is actually pretty simple. The internet is simply a collection of computers connected together by communications hardware, such as routers and network cables.
Whenever you access a web page, watch a video or send an email, there’s another computer somewhere in the world that’s providing the content or acting as the go-between to help you communicate with someone else.
What Is a Server vs a Client
These computers, the ones providing the SERVices, are what we generally refer to as “servers”. The computers that receive those services are called “clients”. See? It’s a pretty simple concept. Servers serve content and services to clients. However, that doesn’t tell us much about the servers themselves. Just what are they exactly?
Servers are Just Computers
Any computer can be a server. Your home computer can be a server. Although your internet service provider probably prohibits the practice on home internet subscriptions. It’s not just traditional desktop computers either. Any network-connected computer can act as a server, client or both.
Rather than being a description of a specific device, the concepts of “client” and “server” describe roles that computers have on a network. For example, if you have an IP security camera, those have server software installed on its tiny embedded computer. When you access the camera, you’re logging into a server that provides you with a video stream.
That being said, not every computer is suitable to act as a server. So often when the word “server” is used, it refers to specialized computers that are built from the ground up to act specifically as servers.
Server Hardware is Special
If you were to venture into the typical server room of a website hosting company, you’d see rows and rows of cabinets. Inside these cabinets, you’d see racks of servers stacked on top of each other. As seen in this picture.
Inside each of these racks, you’ll find a special server-grade motherboard, RAM, CPU and storage. In principle, these are the same components as the ones in your computer. Except, inside servers they’re far more powerful, reliable and energy efficient. After all, these computers are working 24/7, serving millions of requests from clients every day.
This is why server hardware is much more expensive than the stuff you find in a consumer PC. Every minute a server is down may cause thousands of dollars in losses. So it’s worth paying a premium to ensure that the internet services in question remain available.
We won’t go into deep details here, but server hardware stands out in the following main ways:
- Server motherboards support large amounts of RAM. Terabytes worth in many cases!
- Server motherboards often have multiple CPU sockets
- Server CPUs tend to have many CPU cores and large amounts of cache
- Server RAM is usually of a special error-correcting type to ensure stability
- Server power supplies may be redundant, instantly switching over to a backup if the main unit fails
Rack servers also don’t have keyboards, mice, screens or speakers. Instead, they are accessed via the network through the command line or by using a remote desktop application. Although they usually do have the required ports to hook up these peripherals if needed.
Local Servers
A “local” server is one that runs on your local home network, rather than somewhere “out there” on the internet.
There’s a good chance that you have some sort of server application running on one of your home computers and don’t even know it. The aforementioned IP camera embedded software is one example, but there are other applications that run on regular desktop and laptop systems that also fit the bill.
For example, the popular Plex application runs a media server on your local machine. This is like Netflix running on your local network. Calibre acts as a local file server for ebooks and, of course, network-attached storage devices are also a sort of local network server. So, as you can see, servers are everywhere. Even in your home!
Common Server Types
While all servers have the same general job, there are clear subtypes of servers that specialize in different tasks.
Web servers are incredibly common. The website you are reading at this very moment was sent to you by a web server. Your web browser acts as the client and requests website data from the server. It then receives the HTML (Hypertext Markup Language) web page code and renders it to your screen. From there it enters your eyeballs and this information is now in your head. Neat, right?
File servers use the FTP or File Transfer Protocol standard rather than HTML and exist to move files from their own hard drives to yours.
Email servers handle the sending and receiving of email messages. Basically it’s an electronic post office.
The list goes on. There are servers that verify login details, servers that act as a proxy between company computers and the internet, media streaming servers at companies like Netflix and more. As more internet services are invented, we can expect new types of specialized server hardware and software to come along as time goes by.
“Mainframe” vs “Server”
One final point of confusion is the difference between a “mainframe” computer and a server. While a server is essentially a beefed-up desktop computer, mainframes are an entirely different beast.
These computers are much, much more powerful than server hardware. The emphasis on reliability and spare processing capacity is much higher and these computers are usually used for jobs that are mission critical.
Online banking is one example where mainframes may be a better choice. Especially since mainframe computers are built to zip through as many “transactions” as possible. These computers are usually about the size of a large fridge. Often, they’re as big as ten rack-mounted servers.
Are You Being Served?
Hopefully your curiosity about what computer servers are has now been abated. These are just the basics of course, but now at least you know where your memes are coming from before they reach your screen!
